Middle Triassic arc magmatism in the southern Lhasa terrane: Geochronology, petrogenesis and tectonic setting

The voluminous Triassic magmatism within the Lhasa Terrane, Tibetan Plateau, has been studied for decades yet petrogenesis of magmas involved and tectonic setting this associated events remain uncertain. This study presents new zircon U–Pb geochronological, Lu–Hf isotopic, whole-rock geochemical data Middle volcanic rocks southern region terrane. Zircon dating three samples from area yield consistent ages 233.9 ± 1.3, 232.5 1.6, 231.5 1.6 Ma, representing in geochemistry these indicate they are enriched large ion lithophile elements (LILE) light rare earth (LREE). They have high εNd(t) (from +4.3 to +5.4) εHf(t) +16.6 +21.8) values as well low initial 87Sr/86Sr (0.7035–0.7037) values. These characteristics that igneous formed generated by partial melting arc-type mantle wedge material. underwent fractional crystallization but did not assimilate significant amounts ancient crustal material prior emplacement eruption. Combining our with results previous petrological, stratigraphic, paleomagnetic, paleontological indicates magmatic terranes a result tectonism opening Neo-Tethyan Ocean. driving force extension was most likely driven correlated southward-subduction Banggonghu–Nujiang Oceanic plate.